Abstract
abc4 mutant of Arabidopsis (Feldmann T-DNA tag mutant) showed pale green color in young leaves and white color in old leaves. The mutated nuclear gene encoded the 1,4-dihydroxy-2-naphtoic acid prenyltransferase that is an enzyme of phylloquinone biosynthesis, and HPLC analysis revealed that the mutant had no phylloquinone. Photooxidation of P700 of the mutant was completely inhibited, and the reduced-minus-oxidized difference spectrum indicated that the mutant had no P700. In the pale green leaves of the mutant, the ultrastructure of the chloroplast was almost the same to that of the wild type plant. These results suggested that deficiency of phylloquinone in PSI caused abolishment and decrease in the activities of PSI and PSII, respectively, but did not change the ultrastructure of the chloroplast in young leaves.
